Method for belt splice preparation

ABSTRACT

This invention uses a unique tubular cutting tool in a method for separating individual cables from the elastomeric body of a cable-type conveyor belt. The tool bores a cylindrical path through the elastomeric body coaxial with the individual longitudinal reinforcement cables. A transverse cut is then made across the belt width which just intersects the cylindrical paths which have been made around the cables. The elastomeric material can then be removed leaving only the cables exposed. The prepared belt end is then ready for application of a mechanical or vulcanized splice. The tubular cutting tool features both circular and axial cutting edges. The tool can be utilized in a hand drill to allow on-site splice preparation of the conveyor belt.

This invention relates to cable type conveyor belts and moreparticularly to a method of preparing the end of a cable belt forsubsequent application of a mechanical splice. A specific cutting toolsuitable for use in the method is also disclosed.

BACKGROUND OF THE INVENTION

Cable belts are well known in the heavy duty conveyor belt applications.In this type of conveyor belt construction the tension bearing portionof the conveyor belt is a planar set of heavy stranded cables embeddedin an elastomeric carcass. Each of the set of stranded cables areoriented longitudinally parallel to the direction of travel of theconveyor belt. Due to the very high tensile strength of each of thestranded cables the load carrying capability of such a belt is muchhigher than conventional fabric reinforced conveyor belts. The cabletype conveyor belts also are generally of lesser thickness than plied upfabric-reinforced belting since the stranded cables supply all strengthnecessary to the belt. The rubber or elastomeric cover in which thecables are embedded serves only to protect the cables from abrasion andcutting by sharp or abrasive aggregate which may be transported. Thesecable belts are used regularly in mining and other aggregate carryingapplications requiring long overland hauls of very high load capacities.

The disadvantage to the cable belt construction is that the cable beltis extremely difficult to splice due to the problems associated withfastening single cables securely to one another at the ends of the belt.Conventionally the only splice which has been found suitable to thisdate is a vulcanized type splice where the ends of the belt which are tobe fastened together are prepared by stripping back the rubber carcassfrom the cables interleaving the cables from one end with the cables onthe other end and then curing elastomer into place around theinterleaved cables. U.S. Pat. No. 4,235,120 describes one such method ofsplicing. A major disadvantage of cable belt occurs when a break orrupture of the belt occurs during service and that belt must be repairedin the field. Vulcanized splicing in the field is a long, timeconsuming, difficult process since the curing apparatus for vulcanizingthe rubber in the splice area must be transported to the field. Inaddition the preparation of the belt ends is a long, tedious processwhich has always been performed by hand. In the field preparation of acable belt the rubber cover is slit by hand using knives for skiving.The upper and lower covers are painstakingly trimmed back and once thecovers are removed the rubber must be trimmed from around the cableswithout cutting individual strands of the cable. If some of thefilaments of the strand are cut during skiving the cable will unwindthus ruining the splice area. In handcutting around the cables it is adesirable objective to cut as close to the cable as possible while stillleaving a slight layer of rubber on the cables.

It is an object of this invention to provide a method for preparation ofa cable belt end for splicing in which the rubber carcass can beaccurately and uniformly trimmed from around the individual strandedcables of the belt. An advantage of the invention is that the splice canbe made in a fraction of the time that handcutting methods require.Another object is to provide a method which can trim the rubber fromaround the cable to a close tolerance without cutting individualfilaments of the stranded cable.

BRIEF DESCRIPTION OF THE INVENTION

Advantages of the invention can be obtained by using a method forpreparing an end of a cable belt for splicing, said cable belt includingan elastomeric body having embedded therein a plurality of strandedcables aligned in a reinforcement plane extending transversely acrosssubstantially the entire width of said belt, said stranded cablesextending longitudinally of the belt over its entire length, said methodcomprising the steps of: (a) preparing a transverse cross section ofsaid cable belt end exposing an axial cross sectional end of each ofsaid plurality of stranded cables; (b) positioning a cutting toolagainst said cross section of said cable belt and around an end of oneof said plurality of stranded cables, said cutting tool having an insidediameter greater than the cross section of said stranded cable andadapted to cut circumferentially around said stranded cable over apredetermined axial length of said cable; (c) cutting a cylindrical corearound said stranded cable, said cylindrical core extending for apredetermined distance through said elastomeric body along said strandedcable and co-axial therewith; (d) repeating steps (b) and (c) for eachof said plurality of stranded cables: (e) cutting said elastomeric bodyin a cutting plane transverse of and perpendicular to said cable belt,said cutting plane intersecting each of said cylindrical cores aroundeach of said plurality of stranded cables, said cutting plane extendingthrough said elastomeric body at said predetermined distance from saidend of said cable belt to form a separated segment of said elastomericbody; (f) exerting a force in a direction coincident with said plane ofsaid stranded cables and directed away from said end of said cable beltto effect removal of said separated segment of said elastomeric body,thereby exposing said plurality of stranded cables over saidpredetermined distance.

The method of the invention can advantageously be practiced using acutting tool for cutting cylindrical cores in rubber comprising: atubular body having an axis of rotation; a first annular section of saidtubular body with a first co-axial bore therethrough and a sharpcircular cutting edge forming one end of said first annular section;said first annular section being integrally connected to a secondannular section of said tubular body at the end distal said cuttingedge, said second annular section having a second bore coaxial with saidfirst bore and separated therefrom by a first tapered shoulder, and acutting slot extending axially from proximate said first shoulder andincluding a minority of the periphery of said second annular section,said cutting slot having a cutting edge extending axially along one edgeof said cutting slot, a third section of said tubular body integral withsaid second annular section forming a shaft adaptable for gripping saidtool.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the end portion of a cable beltillustrating one cable being skived by the special cutting tool;

FIG. 2 is a perspective view of the belt of FIG. 1 with the elastomericbody removed from around the individual cables;

FIG. 3 is a side view of the cutting tool of the invention showing thecutting slot;

FIG. 4 is an axial cross section of the tool taken along line, 4--4 inFIG. 3 showing the cutting angle of the cutting slot;

FIG. 5 is an axial cross section of the cutting tool of this inventionshowing the circular and longitudinal edges of the tool.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, the cable belt will be generallyreferred to by the reference figure 10. The cable belt 10 is composed ofan elastomeric body 12 with a planar series of cables 14 orientedlongitudinally of the belt. The longitudinal direction is generallyindicated by the arrow 16 and is coincident with the direction of travelof the belt. The arrow 18 indicates the transverse direction as the termis used herein. The cables are aligned in a reinforcement plane 17,transverse of the belt. The reinforcement plane carries the workingtension during service. The individual cables 14 are generally strandedsteel cables. Aromatic polyamide, carbon fiber or filament glass cablesare also materials of which the stranded cables 14 may be made. Anyother metallic or non-metallic material having suitable tensile strengthand tenacity is within the definition of cables useful in cable belts 10as described in this specification. The cables 14 are generally composedof a multiplicity of filaments which has been cabled or stranded intothe finished cable form and are embedded within the elastomeric body 12to form the cable belt 10. It is understood that layers of fabric (notshown) may be incorporated above and/or below the cables 14 in order toprovide protection for the cables from impinging sharp objects whichpenetrate the elastomeric body during service.

The cable belt 10 is being prepared for splicing using the method ofthis invention by preparing a squared off end section 20 in which thecross section of the cables are exposed. The belt, once it has beensquared off, is secured to prevent movement and a circular tubularcutting tool 22 is centered on the axis of each cable 14 in turn. Thecutting tool 22 is rotated by a suitable means for rotation such as asimple hand held dri11 24 shown in FIG. 1. Once the cutting tool 22 hasbeen positioned concentrically around the cable, sufficient pressurealong the axial direction of the cable is applied by the cutting tool22. The rotation of the cutting tool and the axial pressure bores orskives a cylindrical core 26 through the elastomeric body 12 of thecable belt 10 along the periphery of the cable 14. The axial pressureand rotation of the cutting tool 22 is maintained until the cylindricalcore 26 is formed to a desired depth D along the cable length. Thecutting tool 22 is moved successively along each of the cables 14 toform the cylindrical core 26 in the elastomeric body 12 to separate thecable from the body. There is ideally a small annular core 28 of rubberremaining directly adjacent the periphery of each cable 14.

A transverse cut 30 is then made across the belt in direction 18extending through the thickness of the belt and just intersecting thecylindrical cores 26 around each cable 14. The transverse cut 30 can beaccomplished by a conventional rubber cutting knife apparatus or mayutilize a die which is forced through the rubber in a plane above, belowand between the individual cables. Care must be exercised to preventdamage to the cables 14 during this transverse cutting step.

FIG. 2 shows the elastomeric body removed from the exposed cables 14with their rubber cores 28 attached. The separated segment 32 of theelastomeric body 12 is discarded. In preparation for making a mechanicalor vulcanized splice of the cable belt ends a second end of the samebelt 10 or another belt is prepared in an identical manner prior toapplying the splice. The splice may be mechanical or a vulcanizedelastomeric splice. The mechanical splice can be advantageously usedwith this method given the ability of the method of this invention toleave a slight annular core 28 surrounding each cable. This annular core28 assists in distributing the localized attachment stresses generallyassociated with most mechanical splice devices.

An alternative method of removing the separated segment 32 from theelastomeric body 12 after the completion of the cylindrical coreoperation with the cutting tool 22 involves slicing the elastomeric bodytransversely across the belt in a pair of cutting planes 23,25 justtangent to each cylindrical core 26 and parallel to the reinforcementplane 17 of the belt. The transverse cut 30 is then made perpendicularto the planar cuts to remove upper and lower portions of the elastomericbody 12 which are adjacent to the cables 14. The rubber in theinterstices between the individual cables 14 then can be easily removedusing a conventional rubber knife or a simple die-cutting device. Inthis alternative method the separated segment 32 would come in twoplanar segments as well as a series of small segments from theinterstices between the cables 14.

The cutting tool 22 can be a simple boring tool such as is commonly usedin woodworking but it must be recognized that the resilient character ofrubber makes the task of boring in an elastomer a difficult operationparticularly when the driving means is a hand held device such as apower drill 24 where the cutting tool 22 is chucked therein. Theresilience of the rubber makes the centering of the cutting tool aroundthe individual cables a very difficult task. Where a horizontal drillpress is available and the belt end can be securely positioned, a simplecutting tool which has a toothed leading edge very similar to a metalworking or wood working borer may be utilized. However, in the morefrequent circumstance where a field splice is being made, theavailability of such fixed apparatus is very unlikely and the use ofhand held drilling tools are much more likely to be the available motivemeans for the cutting tool 22. In such a circumstance, a very speciallydesigned cutting tool has been found to be preferable in the practice ofthe method of this invention.

FIGS. 3, 4 and 5 illustrate a preferred cutting tool 40 which issuitable for boring cylindrical bores in a solid rubber matrix. Thecutting tool 40 includes a tubular body 42 having an axis of symmetry44. The tubular body is composed of several co-axial segments which liealong the axis 44. The first annular section 46 includes a leading edge48 composed of a sharp circular cutting edge 50. The first annularsection 46 includes also an outward taper 52 extending axially away fromthe cutting edge 50. The first annular section 46 contains a first boreco-axial with axis 44 having an inward taper 56. The taper 56 may bebetween about 10 and 20 degrees, preferably about 12 to 16 degrees. Thetaper 56 compresses the elastomer in the bore to assure a smoothtransition through the shoulder 58 which separates the first bore 54from the second bore 60. The shoulder 58 forms the transition betweenthe first annular section and the second annular section 62. The secondannular section 62 includes an outer surface which tapers at a taperangle 63 sufficient to alleviate the tendency of the rubber to bindduring the passage of the cutting tool therethrough. The taper shouldpreferably be less than 10 degrees, and more preferably between 0.5 and5 degrees. The most preferred taper has been found to be about 1 to 2degrees. The second annular section 62 contains a cutting slot 64 whichextends axially from proximate the first shoulder 58 over a distanceless than the full axial length of the second annular section 62. Thecutting slot 64 covers a minor portion of the circumference of thesecond annular section 62 when an axial cross section is taken. The slotmust be narrower than the diameter of the cable being skived. The slot64 has a cutting edge 66 which is machined at a cutting angle 68. Thecutting edge accomplishes skiving of thin sections of the rubber bodythrough which the cutting tool is passing during the rotation of thecutting tool 40. Referring briefly back to FIG. 1, the slot 64 with thecutting edge 66 provides the cylindrical core 26 around the cables 14 byskiving the thin layer of rubber from the elastomeric body 12 thusseparating the cable from the body and allowing subsequent withdrawal ofthe separated segment 32 from the cable 14. The second shoulder 70 formsthe transition between the second bore 60 and the third bore 72 which iscontained in the third annular segment 74. The third annular segment 74functions as a shaft 75 which can be chucked into the rotational motivemeans such as the hand drill 24. The third bore 72 is an optionalfeature which provides a convenient path for the skived rubber shavingsfrom the slot 64 to escape from the cutting tool. The bore also providesa method to clean rubber out of the tool after boring. The shoulder 70forms the stopping means for limiting the penetration of the tool 40into the belt structure by having the cables 14 impinge on the shoulderduring drilling. The second bore 60 has a diameter equal to or slightlygreater than the cable 14. A slightly greater diameter allows for theinclusion of the annular core 28 of rubber as shown in FIG. 2 to remainon the outer periphery of the cable 14 after cutting is complete.

The leading edge 48 the of the tool is a smooth, non-serrated cuttingsurface which facilitates centering of the cutting tool on theindividual cables 14 by assuring a smooth cutting action during initialcontact of the rubber body 12 with cutting tool 40. The various cuttingedge configurations and tapers on the interior and exterior of thecutting tool may be machined to any suitable angle. However, it has beenfound that in cutting rubber, the cutting edge 66 of the cutting slot 64should be machined at the angle 68 of between 30 and 110 degrees. Apreferred range is between 40 degrees and 90 degrees, and mostpreferably is between about 50 and about 70 degrees. The angle 68 ismeasured relative to plane 5--5 which bisects the slot 64 when viewed inaxial cross section. The taper 56 on the first bore 54 is approximately14 degrees although it is believed to be suitable if it is between 5 and30 degrees. The more preferred taper is between 8 and 20 degrees whilethe range of 12 to 16 degrees is most preferred. The taper 63 on thesecond annular section 62 is approximately one degree but may besuitable if as high as 10 degrees. It is understood that the overallwall thickness of the cutting tool is dependent upon the type of steelutilized and it is generally advantageous to minimize the wall sectionsof each of the annular sections of the tubular body 42 in order tominimize the degree of compression which the rubber of the belt must besubjected to. The compression of the rubber is directly proportional towall thickness. Expressed in another way, the less the wall thickness,the less compression of the rubber and the less friction occurs on theouter periphery of the tubular body of the cutting tool 40.

Various embodiments of the invention have been set forth herein.However, various modifications in the features of construction,combination of elements and arrangement of parts may be envisioned byone skilled in the art. The scope of the invention is intended toinclude such modifications so long as they are encompassed by theappended claims.

What is claimed is:
 1. A method for preparing an end of a cable belt forsplicing, said cable belt including an elastomeric body having embeddedtherein a plurality of stranded cables aligned in a reinforcement planeextending transversely across substantially the entire width of saidbelt, said stranded cables extending longitudinally of the belt over itsentire length, said method comprising the steps of:(a) preparing atransverse cross section of said cable belt end exposing an axial crosssectional end of each of said plurality stranded cables; (b) positioninga tubular cutting tool against said cross section of said cable belt andaround an end of one of said plurality of stranded cables, said cuttingtool having an inside diameter greater than the cross section of saidstranded cable and adapted to cut circumferentially around said strandedcable over a predetermined axial length of said cable; (c) cutting acylindrical core around said stranded cable, said cylindrical coreextending for a predetermined distance through said elastomeric bodyalong said stranded cable and co-axial therewith; (d) repeating steps(b) and (c) for each of said plurality of stranded cables; (e) cuttingsaid elastomeric body in a cutting plane transverse of and perpendicularto said cable belt, said cutting plane intersecting each of saidcylindrical cores around and between each of said plurality of strandedcables, said cutting plane extending through said elastomeric body atsaid predetermined distance from said end of said cable belt to form aseparated segment of said elastomeric body; (f) exerting a force in adirection coincident with said plane of said stranded cables anddirected away from said end of said cable belt to effect removal of saidseparated segment of said elastomeric body, thereby exposing saidplurality of stranded cables over said predetermined distance.
 2. Amethod according to claim 1 wherein said cutting step (c) furthercomprises: rotating said cutting tool while simultaneously; applyingaxial pressure to said cutting tool for a time sufficient to cut acylindrical bore through said elastomeric body over a predetermineddistance along said stranded cable thereby separating said strandedcable from said elastomeric body;
 3. A method according to claim 1wherein said cutting step (e) further comprises: cutting saidelastomeric body in a pair of cutting planes parallel to saidreinforcement plane such that said pair of planes are tangent to saidcylindrical cores formed around each stranded cable, said pair ofcutting planes extending said predetermined distance into said cablebelt from said end; and making a plurality of cuts transverse of andperpendicular to said cable belt through said elastomeric body, saidplurality of cuts intersecting said cutting planes and said cylindricalcores around each of said stranded cables to form a separated segment ofsaid elastomeric body.
 4. A method according to claim 1 wherein saidcutting step (c) uses a cutting tool having a tubular body having anaxis of rotation; a first annular section of said tubular body with afirst co-axial bore therethrough and a sharp circular cutting edgeforming one end of said first annular section; said first annularsection being integrally connected to a second annular section of saidtubular body at the end distal said cutting edge, said second annularsection having a second bore coaxial with said first bore and separatedtherefrom by a first tapered shoulder, and a cutting slot extendingaxially from proximate said first shoulder and including a minority ofthe periphery of said second annular section, said cutting slot having acutting edge extending axially along one edge of said cutting slot, athird section of said tubular body integral with said second annularsection forming a shaft adaptable for gripping said tool.